implemented percentage and decibel view modes for slider

A slider can now hold a float value and display it in the UI converted to
either a percentage or a decibel (still returning a linear float value
programmatically for the rest of the code).

app/widget/slider/floatslider.cpp

@@ -20,8 +20,11 @@
 
 #include "floatslider.h"
 
+#include <QAudio>
+
 FloatSlider::FloatSlider(QWidget *parent) :
-  SliderBase(kFloat, parent)
+  SliderBase(kFloat, parent),
+  display_type_(kNormal)
 {
   connect(this, SIGNAL(ValueChanged(QVariant)), this, SLOT(ConvertValue(QVariant)));
 }
@@ -53,17 +56,108 @@ void FloatSlider::SetDecimalPlaces(int i)
   UpdateLabel(Value());
 }
 
+void FloatSlider::SetDisplayType(const FloatSlider::DisplayType &type)
+{
+  display_type_ = type;
+
+  UpdateLabel(Value());
+}
+
 QString FloatSlider::ValueToString(const QVariant &v)
 {
-  return QString::number(v.toDouble(), 'f', decimal_places_);
+  double val = v.toDouble();
+
+  switch (display_type_) {
+  case kNormal:
+    // Do nothing, skip to the return string at the end
+    break;
+  case kDecibel:
+  {
+    // Convert to decibels and return dB formatted string
+    qreal decibels = QAudio::convertVolume(val, QAudio::LinearVolumeScale, QAudio::DecibelVolumeScale);
+    return QStringLiteral("%1 dB").arg(QString::number(decibels, 'f', decimal_places_));
+  }
+  case kPercentage:
+    // Multiply value by 100 for user-friendly percentage
+    val *= 100.0;
+    return QStringLiteral("%1%").arg(QString::number(val, 'f', decimal_places_));
+  }
+
+  return QString::number(val, 'f', decimal_places_);
 }
 
 QVariant FloatSlider::StringToValue(const QString &s, bool *ok)
 {
-  // Allow both floats and integers for either modes
+  switch (display_type_) {
+  case kNormal:
+    // Do nothing, skip to the return string at the end
+    break;
+  case kDecibel:
+  {
+    bool valid;
+
+    // Remove any instance of "dB" in the string
+    QString decibel_number = s;
+    decibel_number.replace("dB", "", Qt::CaseInsensitive);
+
+    // See if we can get a decimal number out of this
+    qreal decibels = decibel_number.toDouble(&valid);
+
+    if (ok) *ok = valid;
+
+    if (valid) {
+      // Convert from decibel scale to linear decimal
+      return QAudio::convertVolume(decibels, QAudio::DecibelVolumeScale, QAudio::LinearVolumeScale);
+    }
+
+    break;
+  }
+  case kPercentage:
+  {
+    bool valid;
+
+    QString percent_number = s;
+    percent_number.replace("%", "", Qt::CaseInsensitive);
+
+    // Try to get double value
+    double val = percent_number.toDouble(&valid);
+
+    if (ok) *ok = valid;
+
+    // If we could get it, convert back to a 0.0 - 1.0 value and return
+    if (valid) {
+      return val * 0.01;
+    }
+
+    break;
+  }
+  }
+
+  // Just try to convert the string to a double
   return s.toDouble(ok);
 }
 
+double FloatSlider::AdjustDragDistanceInternal(const double &start, const double &drag)
+{
+  switch (display_type_) {
+  case kNormal:
+    // No change here
+    break;
+  case kDecibel:
+  {
+    qreal current_db = QAudio::convertVolume(start, QAudio::LinearVolumeScale, QAudio::DecibelVolumeScale);
+    current_db += drag;
+    qreal adjusted_linear = QAudio::convertVolume(current_db, QAudio::DecibelVolumeScale, QAudio::LinearVolumeScale);
+
+    return adjusted_linear - start;
+  }
+  case kPercentage:
+    return drag * 0.01;
+  }
+
+  return SliderBase::AdjustDragDistanceInternal(start, drag);
+}
+
 void FloatSlider::ConvertValue(QVariant v)
 {
   emit ValueChanged(v.toDouble());

app/widget/slider/floatslider.h

@@ -29,6 +29,12 @@ class FloatSlider : public SliderBase
 public:
   FloatSlider(QWidget* parent = nullptr);
 
+  enum DisplayType {
+    kNormal,
+    kDecibel,
+    kPercentage
+  };
+
   double GetValue();
 
   void SetValue(const double& d);
@@ -39,16 +45,23 @@ public:
 
   void SetDecimalPlaces(int i);
 
+  void SetDisplayType(const DisplayType& type);
+
 protected:
   virtual QString ValueToString(const QVariant& v) override;
 
   virtual QVariant StringToValue(const QString& s, bool* ok) override;
 
+  virtual double AdjustDragDistanceInternal(const double& start, const double& drag) override;
+
 signals:
   void ValueChanged(double);
 
 private slots:
   void ConvertValue(QVariant v);
+
+private:
+  DisplayType display_type_;
 };
 
 #endif // FLOATSLIDER_H

app/widget/slider/sliderbase.cpp

@@ -162,6 +162,12 @@ void SliderBase::UpdateLabel(const QVariant &v)
   }
 }
 
+double SliderBase::AdjustDragDistanceInternal(const double &start, const double &drag)
+{
+  Q_UNUSED(start)
+  return drag;
+}
+
 QString SliderBase::ValueToString(const QVariant &v)
 {
   return v.toString();
@@ -178,23 +184,25 @@ void SliderBase::LabelPressed()
   dragged_ = false;
 
   if (mode_ != kString) {
-    dragged_diff_ = value_.toDouble();
+    dragged_diff_ = 0;
   }
 }
 
 void SliderBase::LabelClicked()
 {
   if (dragged_) {
+    double drag_val = value_.toDouble() + AdjustDragDistanceInternal(value_.toDouble(), dragged_diff_);
+
     // This was a drag
     switch (mode_) {
     case kString:
       // No-op
       break;
     case kInteger:
-      SetValue(qRound(dragged_diff_));
+      SetValue(qRound(drag_val));
       break;
     case kFloat:
-      SetValue(dragged_diff_);
+      SetValue(drag_val);
       break;
     }
   } else {
@@ -227,11 +235,13 @@ void SliderBase::LabelDragged(int i)
 
     dragged_diff_ += real_drag;
 
+    double drag_val = value_.toDouble() + AdjustDragDistanceInternal(value_.toDouble(), dragged_diff_);
+
     // Update temporary value
     if (mode_ == kInteger) {
-      temp_dragged_value_ = qRound(dragged_diff_);
+      temp_dragged_value_ = qRound(drag_val);
     } else {
-      temp_dragged_value_ = dragged_diff_;
+      temp_dragged_value_ = drag_val;
     }
 
     temp_dragged_value_ = ClampValue(temp_dragged_value_);
@@ -260,7 +270,7 @@ void SliderBase::LineEditConfirmed()
     setCurrentWidget(label_);
 
     emit ValueChanged(value_);
-  } else if (require_valid_input_) {
+  } else if (require_valid_input_ && !IsTristate()) {
     QMessageBox::critical(this,
                           tr("Invalid Value"),
                           tr("The entered value is not valid for this field."),

app/widget/slider/sliderbase.h

@@ -61,6 +61,8 @@ protected:
 
   void UpdateLabel(const QVariant& v);
 
+  virtual double AdjustDragDistanceInternal(const double& start, const double& drag);
+
   virtual QString ValueToString(const QVariant &v);
 
   virtual QVariant StringToValue(const QString& s, bool* ok);

app/widget/slider/sliderlabel.cpp

@@ -78,5 +78,7 @@ void SliderLabel::focusInEvent(QFocusEvent *event)
 {
   QWidget::focusInEvent(event);
 
-  emit focused();
+  if (event->reason() == Qt::TabFocusReason) {
+    emit focused();
+  }
 }